This invention relates generally to a colorant composition and a polymer-clay nanocomposite having improved color and appearance comprising a colorant composition. This invention further relates to articles produced from the polymer-clay nanocomposite.
There is much interest in polymer/clay nanocomposites because of the improved properties exhibited by the nanocomposites. For example, U.S. Pat. No. 4,739,007 discloses polyamide/clay nanocomposite materials containing clays intercalated with alkylammonium salts. Polymer/clay nanocomposites typically suffer from poor color and appearance due to the presence of the clay.
One objective of this invention is to provide clays intercalated with colorants and/or optical brighteners that mask the color of the clay and provide polymer/clay nanocomposites that are colorless, white, or slightly colored. It is also an object of this invention to provide clays intercalated with colorants that provide colored polymer/clay nanocomposites.
Colorants or pigments derived from the reaction of a cationic dye and a clay are known. For example, R. Fahn and K. Fenderl, Clay Minerals, 18, 447-458 (1987) disclose pigments derived from montmorillonite clay intercalated with certain cationic dyes. However, incorporation of the pigments into thermoplastic polymer/clay nanocomposites, especially those with processing temperatures well above 200xc2x0 C., is neither contemplated nor disclosed.
Therefore, a need still exists for a colorant composition, a polymer-clay nanocomposite comprising the colorant composition and articles produced from the polymer-clay nanocomposite that have improved color and/or appearance.
In accordance with the purpose(s) of this invention, as embodied and broadly described herein, this invention, in one embodiment, relates to a polymer-clay nanocomposite comprising (i) a melt-processible matrix polymer, and incorporated therein (ii) a colorant composition comprising a clay material intercalated with at least one cationic colorant having a cation group and a chromophore group.
In another embodiment, this invention relates to a polymer-clay nanocomposite comprising (i) a melt-processible matrix polymer, and incorporated therein (ii) an optical brightener composition comprising a clay material intercalated with at least one optical brightener having a cation group and a chromophore group.
In another embodiment, this invention relates to a colorant composition comprising (i) at least one cationic colorant having a cation group and a chromophore group, wherein the cation group is separated from the chromophore group by at least two carbons, and (ii) a clay material intercalated with the cationic colorant.
In yet another embodiment, this invention relates to a composition comprising (i) at least one optical brightener having a cation group and a chromophore group, wherein the cation group is separated from the chromophore group by at least two carbons, and (ii) a clay material intercalated with the optical brightener.
In yet another embodiment, the present invention relates to a process for preparing a polymer-clay nanocomposite comprising (i) preparing an intercalated layered clay material by reacting a swellable layered clay material with a cationic colorant, optical brightener, or a mixture thereof, and (ii) incorporating the intercalated clay material in a matrix polymer by melt processing the matrix polymer with the intercalated clay.
Additional advantages of the invention will be set forth in part in the detailed description, which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory of preferred embodiments of the invention, and are not restrictive of the invention, as claimed.
The present invention may be understood more readily by reference to the following detailed description of the invention and the examples provided therein. It is to be understood that this invention is not limited to the specific processes and conditions described, as specific processes and/or process conditions for processing polymers as such may, of course, vary. It is also understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting.
It must also be noted that, as used in the specification and the appended claims, the singular forms xe2x80x9ca,xe2x80x9d xe2x80x9canxe2x80x9d and xe2x80x9cthexe2x80x9d included plural references unless the context clearly dictates otherwise.
Ranges may be expressed herein as from xe2x80x9caboutxe2x80x9d or xe2x80x9capproximatelyxe2x80x9d one particular value and/or to xe2x80x9caboutxe2x80x9d or xe2x80x9capproximatelyxe2x80x9d another particular value. When such a range is expressed, another embodiment includes from the one particular and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent xe2x80x9cabout,xe2x80x9d it will be understood that the particular value forms another embodiment.
Whenever used in this specification or the claims, the terms set forth shall have the following meanings:
xe2x80x9cColorant(s)xe2x80x9d or xe2x80x9ccolorant composition(s)xe2x80x9d shall mean any substance that imparts color to another material or mixture. Colorants are either dyes or pigments and may be naturally present in a material, admixed with a material or applied to it in solution. xe2x80x9cOptical brightener(s)xe2x80x9d or xe2x80x9cfluorescent brightener(s)xe2x80x9d shall mean any fluorescent organic compound that absorbs mainly UV light and emits it as visible light.
xe2x80x9cPigment(s)xe2x80x9d shall mean any substance that imparts color to another material or mixture and is sometimes used synonymously with xe2x80x9ccolorantxe2x80x9d or xe2x80x9cdye.xe2x80x9d Pigments are usually dry powders and may be organic or inorganic.
xe2x80x9cDye(s)xe2x80x9d shall mean any natural or synthetic organic colorant, which may be either acidic or basic. The distinction between natural dyes and pigments is often arbitrary.
xe2x80x9cChromophore(s)xe2x80x9d shall mean a chemical grouping that when present in an aromatic compound (the chromogen), gives color to the compound by causing a displacement of, or appearance of, absorbent bands in the visible spectrum.
xe2x80x9cClay(s),xe2x80x9d xe2x80x9cclay material(s),xe2x80x9d xe2x80x9cLayered clay(s)xe2x80x9d or xe2x80x9clayered clay material(s)xe2x80x9d shall mean any organic or inorganic material or mixtures thereof, such as a smectite clay mineral, which is in the form of a plurality of adjacent, bound layers. The layered clay comprises platelet particles and is typically swellable.
xe2x80x9cPlatelet particles,xe2x80x9d xe2x80x9cplateletsxe2x80x9d or xe2x80x9cparticlesxe2x80x9d shall mean individual or aggregate unbound layers of the layered clay material. These layers may be in the form of individual platelet particles, ordered or disordered small aggregates of platelet particles (tactoids), and small aggregates of tactoids.
xe2x80x9cDispersionxe2x80x9d or xe2x80x9cdispersedxe2x80x9d is a general term that refers to a variety of levels or degrees of separation of the platelet particles. The higher levels of dispersion include, but are not limited to, xe2x80x9cintercalatedxe2x80x9d and xe2x80x9cexfoliated.xe2x80x9d
xe2x80x9cIntercalatedxe2x80x9d or xe2x80x9cintercalate(s)xe2x80x9d shall mean a layered clay material that includes an intercalant, e.g. cationic colorant, disposed between adjacent platelet particles or tactoids of the layered material.
xe2x80x9cExfoliatexe2x80x9d or xe2x80x9cexfoliatedxe2x80x9d shall mean platelets dispersed predominantly in an individual state throughout a carrier material, such as a matrix polymer. Typically, xe2x80x9cexfoliatedxe2x80x9d is used to denote the highest degree of separation of platelet particles.
xe2x80x9cExfoliationxe2x80x9d shall mean a process for forming an exfoliate from an intercalated or otherwise less dispersed state of separation.
xe2x80x9cNanocomposite(s)xe2x80x9d or xe2x80x9cnanocomposite composition(s)xe2x80x9d shall mean a polymer or copolymer having dispersed therein a plurality of individual platelets obtained from an exfoliated, layered and intercalated clay material.
xe2x80x9cMatrix polymerxe2x80x9d shall mean a thermoplastic or melt-processible polymer in which the clay intercalate is dispersed to form a nanocomposite. In this invention, however, the platelet particles are predominantly exfoliated in the polymer to form a nanocomposite.
The present invention relates generally to a colorant or optical brightener composition comprising a layered clay material that is intercalated with at least one cationic colorant, optical brightener and/or a mixture thereof. This invention also relates generally to a polymer nanocomposite comprising a melt-processible matrix polymer and the composition, and to molded articles, film or fiber produced from the polymer nanocomposite.
One embodiment of this invention relates to colorant compositions comprising a clay material that is intercalated with one or more cationic dyes and/or optical brighteners having a cation group and a chromophore group, wherein the cation group is separated from the chromophore group by at least two carbon atoms. These colorant compositions have exceptional thermal stability and are, therefore, more useful for incorporation into thermoplastic polymers by a wider variety of methods, e.g., the compositions could withstand polymerization conditions. Other structures may also have sufficient thermal stability under processing, e.g., compounding conditions.
In another embodiment, this invention relates to a polymer nanocomposite, preferably a polyester nanocomposite. The desired colorant composition and any additional clay material desired are added to monomers or oligomers, and polymerization processes known in the art prepare the polymer nanocomposite. In yet another embodiment of this invention, the desired colorant compositions and any additional clay material desired are melt-compounded with a melt-processable matrix polymer to form the nanocomposite of this invention.
Many of the suitable clay materials, especially the natural clays, are colored. In an embodiment of this invention, the clay material is intercalated with a sufficient amount of the appropriate one or more cationic dyes to cover the color of the clay in the nanocomposite to produce a colorless or slightly colored nanocomposite. In another embodiment of this invention, the clay material is intercalated with sufficient amount of the appropriate one or more cationic dyes required to impart a desired color to the nanocomposite. In yet another embodiment of this invention, one or more pigments are used in combination to attain the nanocomposite with the desired color. In still another embodiment of this invention, one or more pigments are used in combination with a dye-free clay, which is typically intercalated or treated, to achieve the desired color and nanocomposite properties.
Frequently, achieving the desired appearance requires the use of more than one dye or the combination of dyes and an optical brightener. The dyes and optical brighteners may be co-intercalated into the same clay, optionally with other intercalants, or may be used individually to intercalate clays, optionally with other intercalants, and then combined into the composite, optionally with additional dye-free clay which is typically modified, in the appropriate amounts to achieve the desired appearance. Thus, the range of color and amount of color may vary substantially depending on many factors including choice and concentration of cationic colorants and/or optical brighteners, choice and concentration of clays, choice and concentration of dye-free clay, and choice and concentration of other additives.
The colorant compositions or pigments of this invention may be prepared by intercalating a cationic colorant and/or an optical brightener into the gallery of the layered clay material. Many processes to intercalate materials, especially organic cation salts, into clays are known, and may be used in the process of this invention. Illustrative of these processes is the modification of a layered clay with one or more cationic colorants by the process of dispersing a layered clay into hot water, most preferably from 50 to 80xc2x0 C., adding the desired cationic colorant salts separately or adding a mixture of the cationic colorant salts (neat or dissolved in water or alcohol) with agitation, then blending for a period of time sufficient for the organic cations to exchange most of the metal cations present in the galleries between the layers of the clay material. Then, the pigment is isolated by methods known in the art including, but not limited to, filtration, centrifugation, spray drying, and their combinations.
It is desirable to use a sufficient amount of the organic cation colorant salts to permit exchange of the metal cations in the galleries of the layered particle for organic cations; therefore, at least about 0.5 equivalent of total organic cation salts is used and up to about 3 equivalents of organic cation salts can be used. It is preferred that about 0.5 to 2 equivalents of organic cation colorant salts be used, more preferable about 1.0 to 1.5 equivalents. It is desirable, but not required, to remove most of the metal cation salts and most of the excess organic cation colorant salts by washing and other techniques known in the art.
The particle size of the resulting colorant or pigment is reduced in size by methods known in the art, including, but not limited to, grinding, pulverizing, hammer milling, jet milling, and their combinations. It is preferred that the average particle size be reduced to less than 100 micron in diameter, more preferably less than 50 micron in diameter, and most preferably less than 20 micron in diameter. The process to prepare the colorant composition or pigment may be conducted in a batch, semi-batch, or continuous manner.
Any cationic (basic) colorant may be used in the polymer nanocomposite or in the practice of this invention, and many cationic colorants are known (see for example Colour Index, 3rd Ed., Vol. 1, pp. 1611-1688, The Soc. of Dyers and Colourists, 1997). It has been unexpectedly found that some colorants or pigments have excellent thermal stability and are therefore more generally useful and more generally preferred for the formation of polymer nanocomposites.
More particularly, it has been discovered that colorant or pigment compositions comprising a clay material that is intercalated with a cation (basic) dye in which the cation group or groups are separated from the chromophore group by at least two carbon atoms have unexpectedly good thermal stability and are sufficiently thermally stable to permit the preparation of polymer nanocomposites by in-situ polymerization processes, for example, which typically require prolonged heating at temperature above the melting point of the polymer.
The preferred colorants useful in the practice of this invention correspond to the general formula (I):
[A]xe2x80x94(Xxe2x80x94Rxe2x80x94Y)nxe2x80x83xe2x80x83(I)
wherein
A is a mono-, di-, tri-, or tetra-valent colorant moiety comprising the chromophoric classes of anthraquinones, methines, anthrapyridones, triphenodioxazines, fluorindines, phthaloylpyrrocolines, coumarins, phthaloylacridones, 4-amino-1,8-naphthalimidies, thioxanthrones, 2,5-arylaminoterephthalic acids or esters, benzanthrones, 3,6-diaminopyromellitic acid diimides, quinophthalones, naphthalene 1:4:5:8-tetra carboxylic bis-imides; isothiazoloanthrones, anthrapyrimidines, anthrapyrimidones, indanthrones, phthalocyanines, naphthalocyanines, perinones, 3-aryl-2,5-dioxypyrrolines, 3,4,9,10-perylenetetracarboxylic acid diimides, or 5-arylidene-2-(5H)furanones;
X is a linking group comprising xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94, xe2x80x94SO2xe2x80x94, xe2x80x94CO2xe2x80x94, xe2x80x94CON(R1)xe2x80x94, xe2x80x94SO2N(R1)xe2x80x94, or a covalent bond, wherein R1 is hydrogen, C1-C8 alkyl, aryl, or C5-C7 cycloalkyl;
R is C2-C8 alkylene or xe2x80x94(C2-C8 alkylene)-[(X-(C2-C8 alkylene)]1-3xe2x80x94;
Y is a moiety having the general formula (II): 
xe2x80x83wherein Zxe2x88x92 is a halogen ion; R2 is C1-C8 alkyl or C2-C8 alkenyl; R3 and R4 are independently C1-C8 alkyl, C3-C8 alkenyl, C5-C7 cycloalkyl, or may be combined to produce a moiety having the general formula (III): 
xe2x80x83wherein
X1 is a covalent bond, xe2x80x94CH2xe2x80x94, xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94, xe2x80x94SO2xe2x80x94, or xe2x80x94N(R5)xe2x80x94, wherein R5 is an acyl radical; and n is 1-4.
In the above definitions, the term C1-C8 alkyl is used to denote a straight or branched chain saturated hydrocarbon radical containing one to eight carbon and this radical substituted with C1-C8 alkoxy, aryl or C3-C7 cycloalkyl. The term C3-C8 alkenyl is used to describe a straight or branched chain monovalent hydrocarbon radical having three to eight carbons and containing at least one carbon to carbon double bond. The term C5-C7 cycloalkyl is used to describe a saturated cyclic hydrocarbon monovalent radical containing five to seven carbons and which may be substituted with at least one C1-C8 alkyl group. The term aryl is used to describe a phenyl radical and phenyl substituted with one or more groups selected from C1-C8 alkyl, C1-C8 alkoxy, or halogen. The term C2-C8 alkylene is used to describe a straight or branched chain divalent hydrocarbon radical containing two to eight carbon atoms. The term acyl is used to describe the following structures: xe2x80x94COxe2x80x94(C1-C8 alkyl), xe2x80x94CO-(aryl), xe2x80x94CO2xe2x80x94(C1-C8 alkyl), xe2x80x94SO2xe2x80x94(C1-C8 alkyl), xe2x80x94SO2-aryl, and xe2x80x94SO2xe2x80x94(C5-C7 cycloalkyl). The term halogen is used to denote fluorine, chlorine, bromine, and iodine.
Suitable optical brighteners are selected from the classes of stilbenes, styrylbenoxazoles, coumarins, benzocoumarins, 1,4-bis(benzoxazolyl-2xe2x80x2-yl)-naphthalones, naphthalimides, thiophene oxazoics, pyrazolines, xanthenes, and the like, and have cationic (basic) sites rendering them suitable for dyeing acrylic fibers, for example (see Colour Index, 3rd Ed., Vol. 2, pp. 2745-2771, The Soc. of Dyers and Colourists, 1971).
The colorant composition and polymer-clay nanocomposite of the present invention comprise less than about 25 weight percent, preferably from about 0.5 to about 20 weight percent, more preferably from about 0.5 to about 15 weight percent, and most preferably from about 0.5 to about 10 weight percent of a swellable layered clay material that is intercalated with a cationic colorant.
The intercalated clay material of the colorant composition has platelet particles, which are dispersed in the polymer to form the polymer-clay nanocomposite. The polymer nanocomposite is preferably a polyester polymer or copolymer nanocomposite having an I.V. of at least 0.7 dL/g as measured in phenol/tetrachloroethane (60 wt. %/40 wt. %) at 25xc2x0 C. The amount of platelet particles is determined by measuring the amount of silicate residue in the ash of the polymer/platelet composition when treated in accordance with ASTM D5630-94.
Useful clay materials include natural, synthetic, and modified phyllosilicates. Illustrative of such natural clays is smectite clays, such as montmorillonite, saponite, hectorite, mica, vermiculite, bentonite, nontronite, beidellite, volkonskoite, saponite, magadite, kenyaite, and the like. Illustrative of such synthetic clays is synthetic mica, synthetic saponite, synthetic hectorite, and the like. Illustrative of such modified clays are fluoronated montmorillonite, fluoronated mica, and the like. Suitable clays are available from various companies including Nanocor, Inc., Southern Clay Products, Kunimine Industries, Ltd., and Rheox.
Preferred clay materials are phyllosilicates of the 2:1 type having a cation exchange capacity of 0.3 to 2.0 milliequivalents per gram of mineral (meq/g). The most preferred clay materials are smectite clay minerals, particularly bentonite or montmorillonite, more particularly Wyoming-type sodium montmorillonite or Wyoming-type sodium bentonite.
Generally, the layered clay materials useful in this invention are an agglomeration of individual platelet particles that are closely stacked together like cards, in domains called tactoids. The individual platelet particles of the clays preferably have thickness of less than about 2 nm and diameter in the range of about 10 to about 3000 nm. Preferably, the clays are dispersed in the polymer so that most of the clay material exists as individual platelet particles, small tactoids, and small aggregates of tactoids. Preferably, a majority of the tactoids and aggregates in the polymer/clay nanocomposites of the present invention will have thickness in its smallest dimension of less than about 20 nm. Polymer/clay nanocomposite compositions with the higher concentration of individual platelet particles and fewer tactoids or aggregates are preferred.
Moreover, the layered clay materials are typically swellable free flowing powders having a cation exchange capacity from about 0.3 to about 3.0 meg/q, more preferably from 0.9 to about 1.5 meq/g and most preferably from 0.95 to about 1.25 meq/g. The clay may have a wide variety of exchangeable cations present in the galleries between the layers of the clay, including, but not limited to, cations comprising the alkaline metals (group IA), the alkaline earth metals (group IIA), and their mixtures. The most preferred cation is sodium; however, any cation or combination of cations may be used provided that most of the cations are exchanged for organic colorant cations during the process of this invention.
Other non-clay materials having the above-described ion-exchange capacity and size, such as chalcogens, may also be used as the source of platelet particles under the present invention. Chalcogens are salts of a heavy metal and group VIA (O, S, Se, and Te). These materials are known in the art and do not need to be described in detail here.
If desired, the clay material may be treated for the purposes of aiding dispersion or exfoliation in a polymer and/or improving the strength of the polymer/clay interface, and any treatment that achieves the above goals may be used before, during, or after intercalation of the clay with one or more colorants, optical brighteners, and/or their mixtures.
Examples of useful treatments include intercalation of the clay with water soluble or water insoluble polymers, oligomers, monomers, or organic compounds, silane compounds, metals, organometallics, other organic cations, and/or their combinations, dispersion of the clay into a solvent or dispersing aid, compounding into oligomeric materials, adding or mixing dispersing aids, and the like.
Treatment of the clay can be accomplished prior to the addition of a water-dispersible polymer to the clay material, during the dispersion of the clay with a water-soluble polymer or during a subsequent melt blending or melt fabrication step.
Examples of useful pretreatment with polymers and oligomers include those disclosed in U.S. Pat. Nos. 5,552,469 and 5,578,672, incorporated herein by reference. Examples of useful polymers for treating the intercalated clays include polyvinyl pyrrolidone, polyvinyl alcohol, polyethylene glycol, polytetrahydrofuran, polystyrene, polycaprolactone, certain water-dispersible polyesters, Nylon-6, poly(m-xylylene adipamide) and the like.
Examples of useful pretreatment with organic reagents and monomers include those disclosed in EP 780,340 A1, incorporated herein by reference. Examples of useful organic reagents and monomers for intercalating the swellable layered clay include dodecylpyrrolidone, caprolactone, caprolactam, ethylene carbonate, ethylene glycol, bishydroxyethyl terephthalate, dimethyl terephthalate, adipic acid, m-xylylenediamine and the like or mixtures thereof.
Examples of useful pretreatment with silane compounds include those treatments disclosed in WO 93/11190, incorporated herein by reference. Examples of useful silane compounds includes (3-glycidoxypropyl)trimethoxysilane, 2-methoxy(polyethyleneoxy)propyl heptamethyl trisiloxane, octadecyl dimethyl (3-trimethoxysilylpropyl) ammonium chloride and the like.
Organic cations that can be used to intercalate the clay material of the colorant composition and/or nanocomposite of this invention are derived from organic cation salts, preferably onium salt compounds. Organic cation salts useful for the colorant composition and nanocomposite of this invention may generally be represented as follows: 
wherein
M is either nitrogen or phosphorous; Xxe2x88x92 is a halide, hydroxide, or acetate anion, preferably chloride and bromide; and R1, R2, R3, and R4 are independently organic and oligomeric ligands or may be hydrogen.
Examples of useful organic ligands include, but are not limited to, linear or branched alkyl groups having 1 to 22 carbon atoms, more preferably 1 to 12 carbon atoms, aralkyl groups which are benzyl and substituted benzyl moieties including fused-ring moieties having linear chains or branches of 1 to 100 carbon atoms, more preferably 1 to 12 carbon atoms, in the alkyl portion of the structure, aryl groups such as phenyl and substituted phenyl including fused-ring aromatic substituents, beta, gamma unsaturated groups having six or less carbon atoms, and alkyleneoxide groups having 2 to 6 carbon atoms, more preferably 3 to 5 carbon atoms. Examples of useful oligomeric ligands include, but are not limited to, poly(alkylene oxide), polystyrene, polyacrylate, polycaprolactone, and the like.
Useful organic cations for this invention also include, but are not limited to, alkyl ammonium ions, such as dodecyl ammonium, octadecyl ammonium, bis(2-hydroxyethyl)octadecyl methyl ammonium, octadecyl benzyl dimethyl ammonium, tetramethyl ammonium, and the like, and alkyl phosphonium ions such as tetrabutyl phosphonium, trioctyl octadecyl phosphonium, tetraoctyl phosphonium, octadecyl triphenyl phosphonium, and the like.
Illustrative examples of suitable polyalkoxylated ammonium compounds include the hydrochloride salts of polyalkoxylated amines such as JEFFAMINE (of Huntsman Chemical), namely, JEFFAMINE-506, which was analyzed to be an oligooxyethlene amine with number average molecular weight of about 1100 g/mol, and JEFFAMINE 505 which was analyzed to be an oligooxypropylene amine with number average molecular weight of about 640 g/mol. Other hydrochloride salts of polyalkoxylated amines include the hydrochloride salt of ETHOMEEN 18/25 (of Akzo Chemie America), which is octadecyl bis(polyoxyethylene[15])amine, wherein the numbers in brackets refer to the total number of ethylene oxide units. ETHOQUAD (of Akzo Chemie America), or, namely, ETHOQUAD 18/25, which is octadecyl methyl bis(polyoxyethylene[15]) ammonium chloride is an example of a salt of a polyalkoxylated amine. Preferred polyalkoxylated organic cations for use in polyesters, such as poly(ethylene terephthalate), are polyalkoxylated ammonium compounds.
Numerous methods to modify layered clays with organic cations are known, and any of these may be used in the process of this invention.
If desired, a dispersing aid may be present during or prior to the formation of the composite by melt mixing for the purposes of aiding exfoliation of the treated or untreated swellable layered particles into the polymer. Many such dispersing aids are known, covering a wide range of materials including water, alcohols, ketones, aldehydes, chlorinated solvents, hydrocarbon solvents, aromatic solvents, and the like or combinations thereof.
It should be appreciated that on a total composition basis, dispersing aids and/or pretreatment compounds may account for significant amount of the total composition, in some cases up to about 30 weight percent. While it is preferred to use as little dispersing aid/pretreatment compounds as possible, the amounts of dispersing aids and/or pretreatment compounds may be as much as about 8 times the amount of the platelet particles.
This invention also relates to polymer nanocomposites comprising the colorant compositions of this invention. The polymer nanocomposite compositions of this invention may comprise a wide range of materials depending on the pigment and polymer selected. Any melt processible polymer may be used in this invention. Illustrative of melt-processible polymers are polyesters, polyetheresters, polyamides, polyesteramides, polyurethanes, polyimides, polyetherimides, polyureas, polyamideimides, polyphenyleneoxides, phenoxy resins, epoxy resins, polyolefins, polyacrylates, polystyrenes, polyethylene-co-vinyl alcohols (EVOH), and the like or their combinations and blends. Although the preferred polymers are linear or nearly linear, polymers with other architectures, including branched, star, cross-linked and dendritic structures may be used, if desired.
The preferred polymers include those materials that are suitable for use in the formation of multilayer structures with polyesters, and include polyesters, polyamides, polyethylene-co-vinyl alcohols (such as EVOH) and similar or related polymers and/or copolymers. The preferred polyester is poly(ethylene terephthalate) (PET) or a copolymer thereof. The preferred polyamide is poly(m-xylylene adipamide or a copolymer thereof.
Suitable polyesters include at least one dibasic acid and at least one glycol. The primary dibasic acids are terephthalic, isophthalic, naphthalenedicarboxylic, 1,4-cyclohexanedicarboxylic acid and the like. The various isomers of naphthalenedicarboxylic acid or mixtures of isomers may be used, but the 1,4-, 1,5, 2,6-, and 2,7-isomers are preferred. The 1,4-cyclohexanedicarboxylic acid may be in the form of cis, trans, or cis/trans mixtures. In addition to the acid forms, the lower alkyl esters or acid chlorides may be also be used.
The polyester may be prepared from one or more of the following dicarboxylic acids or glycols.
The dicarboxylic acid component of the polyester may optionally be modified with up to about 50 mole percent of one or more different dicarboxylic acids. Such additional dicarboxylic acids include dicarboxylic acids having from 6 to about 40 carbon atoms, and more preferably dicarboxylic acids selected from aromatic dicarboxylic acids preferably having 8 to 14 carbon atoms, aliphatic dicarboxylic acids preferably having 4 to 12 carbon atoms, or cycloaliphatic dicarboxylic acids preferably having 8 to 12 carbon atoms. Examples of suitable dicarboxylic acids include phthalic acid, terephthalic acid, isophthalic acid, naphthalene-2,6-dicarboxylic acid, cyclohexanedicarboxylic acid, cyclohexanediacetic acid, diphenyl-4,4xe2x80x2-dicarboxylic acid, phenylene (oxyacetic acid) succinic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, and the like. Polyesters may also be prepared from two or more of the above dicarboxylic acids.
Typical glycols used in the polyester include those containing from two to about ten carbon atoms. Preferred glycols include ethylene glycol, propanediol, 1,4-butanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, diethylene glycol, neopentyl glycol, and the like. The glycol component may optionally be modified with up to about 50 mole percent, preferably up to about 25 mole percent, and more preferably up to about 15 mole percent of one or more different diols. Such additional diols include cycloaliphatic diols preferably having 6 to 20 carbon atoms or aliphatic diols preferably having 3 to 20 carbon atoms. Examples of such diols include: diethylene glycol, neopentyl glycol, triethylene glycol, 1,4-cyclohexanedimethanol, propane-1,3-diol, butane-1,4-diol, pentane-1,5-diol, hexane-1,6-diol, 3-methylpentanediol-(2,4), 2-methylpentanediol-(1,4), 2,2,4-trimethylpentane-diol-(1,3), 2-ethylhexanediol-(1,3), 2,2-diethylpropane-diol-(1,3), hexanediol-(1,3), 1,4-di-(2-hydroxyethoxy)-benzene, 2,2b-is-(4-hydroxycyclohexyl)-propane, 2,4-dihydroxy-1,1,3,3-tetramethyl-cyclobutane, 2,2-bis-(3-hydroxyethoxyphenyl)-propane, 2,2-bis-(4-hydroxypropoxyphenyl)-propane and the like. Polyesters may also be prepared from two or more of the above diols.
Small amounts of multifunctional polyols such as trimethylolpropane, pentaerythritol, glycerol and the like may be used, if desired. When using 1,4-cyclohexanedimethanol, it may be the cis, trans or cis/trans mixtures. When using phenylenedi(oxyacetic acid), it may be used as 1,2; 1,3; 1,4 isomers, or mixtures thereof.
The polymer may also contain small amounts of trifunctional or tetrafunctional comonomers to provide controlled branching in the polymers. Such comonomers include trimellitic anhydride, trimethylolpropane, pyromellitic dianhydride, pentaerythritol, trimellitic acid, trimellitic acid, pyromellitic acid and other polyester forming polyacids or polyols generally known in the art.
Suitable polyamides include partially aromatic polyamides, aliphatic polyamides, wholly aromatic polyamides and/or mixtures thereof. By xe2x80x9cpartially aromatic polyamide,xe2x80x9d it is meant that the amide linkage of the partially aromatic polyamide contains at least one aromatic ring and a nonaromatic species. Suitable polyamides have an article forming molecular weight and preferably an I.V. of greater than 0.4.
Preferred wholly aromatic polyamides comprise in the molecule chain at least 70 mole % of structural units derived from m-xylylene diamine or a xylylene diamine mixture comprising m-xylylene diamine and up to 30% of p-xylylene diamine and an aliphatic dicarboxylic acid having 6 to 10 carbon atoms, which are further described in Japanese Patent Publications No. 1156/75, No. 5751/75, No. 5735/75 and No. 10196/75 and Japanese Patent Application Laid-Open Specification No. 29697/75.
Polyamides formed from isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, meta- or para-xylylene diamine, 1,3- or 1,4-cyclohexane(bis)methylamine, aliphatic diacids with 6 to 12 carbon atoms, aliphatic amino acids or lactams with 6 to 12 carbon atoms, aliphatic diamines with 4 to 12 carbon atoms, and other generally known polyamide forming diacids and diamines can be used. The low molecular weight polyamides may also contain small amounts of trifunctional or tetrafunctional comonomers such as trimellitic anhydride, pyromellitic dianhydride, or other polyamide forming polyacids and polyamines known in the art.
Preferred partially aromatic polyamides include, but are not limited to poly(m-xylylene adipamide), poly(m-xylylene adipamide-co-isophthalamide), poly(hexamethylene isophthalamide), poly(hexamethylene isophthalamide-co-terephthalamide), poly(hexamethylene adipamide-co-isophthalamide), poly(hexamethylene adipamide-co-terephthalamide), poly(hexamethylene isophthalamide-co-terephthalamide) and the like or mixtures thereof. More preferred partially aromatic polyamides include, but are not limited to poly(m-xylylene adipamide), poly(hexamethylene isophthalamide-co-terephthalamide), poly(m-xylylene adipamide-co-isophthalamide), and/or mixtures thereof. The most preferred partially aromatic polyamide is poly(m-xylylene adipamide).
Preferred aliphatic polyamides include, but are not limited to poly(hexamethylene adipamide) and poly(caprolactam). The most preferred aliphatic polyamide is poly(hexamethylene adipamide). Partially aromatic polyamides are preferred over the aliphatic polyamides where good thermal properties are crucial.
Preferred aliphatic polyamides include, but are not limited to polycapramide (nylon 6), poly-aminoheptanoic acid (nylon 7), poly-aminonanoic acid (nylon 9), polyundecane-amide (nylon 11), polyaurylactam (nylon 12), poly(ethylene-adipamide) (nylon 2,6), poly(tetramethylene-adipamide) (nylon 4,6), poly(hexamethylene-adipamide) (nylon 6,6), poly(hexamethylene-sebacamide) (nylon 6,10), poly(hexamethylene-dodecamide) (nylon 6,12), poly(octamethylene-adipamide) (nylon 8,6), poly(decamethylene-adipamide) (nylon 10,6), poly(dodecamethylene-adipamide) (nylon 12,6) and poly(dodecamethylene-sebacamide) (nylon 12,8).
The most preferred polyamides include poly(m-xylylene adipamide), polycapramide (nylon 6) and poly(hexamethylene-adipamide) (nylon 6,6). Poly(m-xylylene adipamide) is a preferred polyamide due to its availability, high barrier, and processability.
The polyamides are generally prepared by processes which are well known in the art.
Although not necessarily preferred, the polymers of the present invention may also include additives normally used in polymers. Illustrative of such additives known in the art are carbon black, glass fibers, fillers, impact modifiers, antioxidants, stabilizers, flame retardants, reheat aids, crystallization aids, acetaldehyde reducing compounds, recycling release aids, oxygen scavengers, plasticizers, nucleators, mold release agents, compatibilizers, and the like, or their combinations.
All of these additives and many others and their use are known in the art and do not require extensive discussion. Therefore, only a limited number will be referred to, it being understood that any of these compounds can be used in any combination so long as they do not hinder the present invention from accomplishing its objects.
This invention also relates to articles prepared from the nanocomposite material of this invention, including, but not limited to film, fibers, sheet, pipes, tubes, profiles, molded articles, preforms, stretch blow molded films and containers, injection blow molded containers, extrusion blow molded films and containers, thermoformed articles and the like. The containers are preferably bottles. The utility of nanocomposites has been established. The advantages of the nanocomposites of this invention include the preparation of molded articles, films, and fibers with improved appearance. In addition, the colored molded articles, films, and fibers of this invention have excellent light fastness and color stability.
The bottles and containers of this invention may also provide increased shelf storage life for contents, including beverages and food that are sensitive to the permeation of gases. Articles, more preferably containers, of the present invention may display a gas transmission or permeability rate (oxygen, carbon dioxide, water vapor) at least 10% lower (depending on clay concentration) than that of similar containers made from clay-free polymer, resulting in correspondingly longer product shelf life provided by the container. Desirable values for the sidewall modulus and tensile strength may also be maintained.
The articles may also be multilayered. Preferably, the multilayered articles have a nanocomposite material disposed intermediate to other layers, although the nanocomposite may also be one layer of a two-layered article. In embodiments where the nanocomposite and its components are approved for food contact, the nanocomposite may form the food contact layer of the desired articles. In other embodiments it is preferred that the nanocomposite be in a layer other than the food contact layer.
The multilayer articles may also contain one or more layers of the nanocomposite composition of this invention and one or more layers of a structural polymer. A wide variety of structural polymers may be used. Illustrative of structural polymers are polyesters, polyetheresters, polyamides, polyesteramides, polyurethanes, polyimides, polyetherimides, polyureas, polyamideimides, polyphenyleneoxides, phenoxy resins, epoxy resins, polyolefins, polyacrylates, polystyrene, polyethylene-co-vinyl alcohols (EVOH), and the like or their combinations and blends. The preferred structural polymers are polyesters, such as poly(ethylene terephthalate) and its copolymers.
In another embodiment of this invention, the polymer-clay nanocomposite and the molded article or extruded sheet may be formed at the same time by co-injection molding or co-extruding.
Another embodiment of this invention is the combined use of silicate layers uniformly dispersed in the matrix of a high barrier thermoplastic together with the multilayer approach to packaging materials. By using a layered clay, the amount of material that is needed to generate a specific barrier level in the end application is greatly reduced.
Since the high barrier material is often the most expensive component in multilayer packaging, a reduction in the amount of this material used can be quite beneficial. With the nanocomposite layer being sandwiched between two outer polymer layers, the surface roughness is often considerably less than for a monolayer nanocomposite material. Thus, with a multilayer approach, the level of haze is reduced.